mikeraz@hive:~> perl -e 'my $x = (.0425 * 2) + .0025; print $x - (.042
+5 * 2) - .0025, $/;'
2.16840434497101e-18
mikeraz@hive:~>
[download]

Silly me would expect something like 0 to be printed. Why the 2.16840434497101e-18? (OK, round it off and you have 0, but ....)

Digging into this I tried something "simplier" and got more confused:

mikeraz@hive:~> perl -e 'print ((.0425*2) + .0025 ) - ((.0425*2) + .00
+25 ); print $/;'
0.0875
mikeraz@hive:~>
[download]